Traditionally, “plain old telephone service” or “POTS” has been facilitated using a low voltage, low current combination of DC and AC signals transmitted over the telephone network to a local telephone. This has been sufficient to power the functionality of a simple telephone and to generate, transmit, and receive modulated AC signals for voice transmission. The electrical current necessary to enable operation of a local telephone is typically about 25 milliamps.
Modern telephones have an expanded array of features such as visual displays, speakerphones, recording/messaging, portable handset and other capabilities. The power necessary to enable these capabilities exceeds what is available from the telephone network at a local telephone. Simply stated, telephone network current is not sufficient to power anything but the telephone itself. As a result, one or more additional external power supply units are required to furnish the necessary capability. Frequently, these power supply units take the form of AC/DC adaptors that are plugged into a standard 110 AC wall socket and the output of which is connected to the telephone or peripheral devices. These so-called “wall-warts” provide the additional power required to support the added functions/capabilities and devices (e.g., battery operated wireless handset) associated with the telephone.
Likewise if electronic “data” services, such as ISDN or DSL, are to be transported on the same pair of conductors to, or near to, the local telephone instrument, yet another “wall-wart” is almost certainly required to power the associated modem device. For convenience these telephone instruments and modem power sources are referred to as being “AC line powered.”
While wall-warts are unsightly and cumbersome they are acceptable for most purposes to provide the additional power (i.e., power beyond what is supplied by the CO/CB/SLC/IAD/PBX over the telephone network) to AC line powered devices.
Nevertheless, there are situations where some telephone-related capability or feature is desired that requires additional power but is located in an environment where AC line power is not available. This can be the case wherever wiring was put in place specifically for telephone applications. Existing incarceration facilities, particularly older prisons and jails, are one example of such an environment. These institutions typically provide POTS telephone services as an amenity for the inmates to conduct necessary and/or interpersonal communications with those on the “outside.” Recently, such institutions have desired to supplement POTS service with additional capabilities. For example, it is highly desirable to increase the accuracy of inmate identification required to access outside phone service by using fingerprint, barcode, RFID, or other types of readers that can identify or verify the inmate by thumb print, palm print, voice print, retinal scan, or another idiosyncratic physical characteristic, or information embedded within a wristband. It is also desirable to enable a telephone with visual two-way camera and picture capability so that the phone can be used as a vehicle for remote visitation from a site near to or far from that of incarceration to avoid excess prisoner movement.
Penal institutions are also finding it increasingly desirable to provide limited Internet or more commonly a restricted service Intranet access to inmates for purposes of accessing an inmate account, conducting transactions, etc., all of which require a modem or similar device to connect to the Intranet via the telephone network. All of these peripheral devices require additional power. A typical peripheral device may require about 60-70 milliamps at some low voltage such as 3-12 VDC. When one or more of these peripheral devices are desired, power requirements may exceed more than 125 milliamps. The equivalent power required for these devices is far in excess of the 25 milliamps available and intended to operate the telephone itself. The DC current available from the telephone network typically barely exceeds the 18-20 milliamp minimum requirement recommended for reasonable conversation quality.
Due to the understandably unique requirements of such facilities, certain infrastructure features available in other buildings, e.g., crawl spaces, hollow walls, AC outlets, are simply not permitted adjacent to or near the physical locations where a telephone or telephone and data device may be desired or needed. Absent the access that may be available in a more typical structure the cost of rewiring for example from a 25-pair cable distributed to many cell blocks and individual station locations to separate CAT-5 cables is simply cost prohibitive, often by orders of magnitude. Likewise the cost to provide new AC power near to the required location, and provide that power source with appropriate physical security for both the outlets, the ‘wall-warts’, and the low voltage from the warts to the actual instruments is usually little short of astronomic. And neither option, even if financially possible, could be accomplished in a time frame similar to that required in a commercial building situation due to the security, controlled access, and physical detritus and debris related to such an undertaking.
Nevertheless, there are emerging pressures (e.g., service delivery, social pressure, cost containment, and manpower reduction reasons) to provide newer telephony related and additional service delivery instruments to these same facilities and difficult locations.
In the absence of available AC power, there are two possible solutions. First, replace the existing POTS, or POTS-like wire pair with either a larger gauge wire or greater number of conductors to each telephone to reduce the resistance to current and facilitate the delivery of greater power to the telephone location. For example, a single UTP could be replaced with a full CAT5 quad pair cable. In many inmate or similar facilities, this is not realistic or perhaps even possible for many of the same reasons that it is not possible to supply AC power.
More recently, it has been proposed to “bleed” a small amount of excess current not required for powering the telephone to charge one or more local batteries that would then be used to provide power to the device (e.g. fingerprint reader) supplying the supplemental capability or feature. This implementation has the disadvantage of requiring a ‘recharge’ time period between instances of device use and cannot be relied upon to provide adequate power in situations of high-use or unexpected use patterns. Using a fingerprint reader as an example, the taking of a fingerprint reading and transmitting that information through the network for verification would result in at least some discharge of the battery while powering the fingerprint reader. Since the fingerprint reader is likely to require much more power than is available from the telephone line to charge the battery, the state of the battery charge will be diminished and will eventually, through constant use, be unable to provide adequate power to operate the fingerprint reader. The device user must now wait some period of time until the battery has time to recharge to a usable threshold before the user can continue his use of the device. A simple misdial of the telephone number and subsequent redial by the user could possibly cause enough discharge of the supply battery to fail the redial attempt which is deemed to be unacceptable operation for most applications.
The use of various example identification enhancement devices mentioned above entails a variety of, typically low speed, controls and communications protocols to, for example, enable and disable a device, provide operational instructions to the device user, and the communication of results or other output from the device to a decision making point such as a centralized control system.
In the current implementations of many of these devices they are always powered whether needed or not, instructions to the user are often provided by playback of a verbal recording from a centralized control system, and the device results are transmitted via DTMF or other audible signaling means. The local telephone instrument is commonly utilized to provide the user instructions which tends to extend the call setup time but in any case prevents the use of the local telephone for its primary purpose when being used to provide instructions. Likewise when the external device such as a biometric characteristic reader is reporting its findings by the use of DTMF tones additional time is required within the overall call setup process. It is no longer an over-zealous concept to deactivate power using devices when not actively performing a function but most current biometric devices will, at best, move to some form of lower power state when not actively performing their respective biometric functions but generally have no means to deactivate when not required for a particular, or over an extended, period of time. The use of DTMF signaling to communicate results can have the additional disadvantage of providing audible clues to inmates in a penal institution situation or for third parties to record otherwise secure information. In either case the information can later be mimicked or used for unintended purposes.
Accordingly, a need exists to supply additional power over the existing delivery system infrastructure to provide greater power at the local telephone location to enable both the normal operation of the telephone and additional capabilities, features or devices. Likewise a need exists to provide some level of control and signaling over that same delivery system that does not use the bandwidth originally provided for telephone conversations. It is with respect to these and other considerations that embodiments of the present invention have been made. Although relatively specific problems have been discussed, it should be understood that embodiments of the present invention should not be limited to solving the specific problems identified in the background.